The present invention relates to polymerase chain reaction (PCR) instruments, particularly to a PCR thermocycler, and more particularly to a sleeve-type silicon thermocycler having improved thermal performance.
Most PCR instruments are large bench top systems that can do large numbers of samples, are relatively slow, and use large amounts of electrical power. Recently, efforts have been directed to the development of miniature PCR chambers which utilize so-called sleeve-type silicon reaction chambers involving doped polysilicon for heating and bulk silicon for convective cooling. The sleeve-type reaction chambers are exemplified by U.S. Pat. No. 5,589,136 issued Dec. 31, 1996, as well as copending U.S. application Ser. No. 08/489,819, filed Jun. 13, 1995, entitled “Diode Laser Heated Micro-Reaction Chamber With Sample Detection Means,” and U.S. application Ser. No. 08/763,465, filed Dec. 11, 1996, entitled “Microfabricated Sleeve Devices for Chemical Reactions,” each assigned to the same assignee.
The present invention provides an improved or advanced sleeve-type silicon PCR chamber by reducing the thermal mass and increasing the surface area of the sleeve for cooling, thereby increasing the speed and the efficiency thereof. This is carried out by etching grooves along the faces of the sleeve and etching a series of grooves on the interior surfaces that connect with the face grooves. The grooves are anisotropically etched in the silicon wafers simultaneously with the formation of the chamber features of the sleeve, such that the inside grooves are etched with the chamber, but the outside grooves are etched separately.